Techniques > Briefs
> Exterior Paint
Paint Removal Precautions
Historic Buildings for Cosmetic Reasons
Because paint removal is a difficult and painstaking process,
a number of costly, regrettable experiences have occurred
and continue to occur for both the historic building and
the building owner. Historic buildings have been set on fire with
blow torches; wood irreversibly scarred by sandblasting or by
harsh mechanical devices such as rotary sanders and rotary wire
strippers; and layers of historic paint inadvertently and unnecessarily
removed. In addition, property owners, using techniques that substitute
speed for safety, have been injured by toxic lead vapors or dust
from the paint they were trying to remove or by misuse of the
paint removers themselves.
Owners of historic properties considering paint removal should
also be aware of the amount of time and labor involved. While
removing damaged layers of paint from a door or porch railing
might be readily accomplished within a reasonable period of time
by one or two people, removing paint from larger areas of a building
can, without professional assistance, easily become unmanageable
and produce less than satisfactory results. The amount of work
involved in any paint removal project must therefore be analyzed
on a case-by-case basis. Hiring qualified professionals will often
be a cost-effective decision due to the expense of materials,
the special equipment required, and the amount of time involved.
Further, paint removal companies experienced in dealing with the
inherent health and safety dangers of paint removal should have
purchased such protective devices as are needed to mitigate any
dangers and should also be aware of State or local environmental
and/or health regulations for hazardous waste disposal.
All in all, paint removal is a messy, expensive, and potentially
dangerous aspect of rehabilitating or restoring historic buildings
and should not be undertaken without careful thought concerning
first, its necessity, and second, which of the available recommended
methods is the safest and most appropriate for the job at hand.
If existing exterior paint on wood siding, eaves, window sills,
sash, and shutters, doors, and decorative features shows no evidence
of paint deterioration such as chalking, blistering, peeling,
or cracking, then there is no physical reason to repaint, much
less remove paint! Nor is color fading, of itself, sufficient
justification to repaint a historic building.
The decision to repaint may not be based altogether on paint
failure. Where there is a new owner, or even where ownership has
remained constant through the years, taste in colors often changes.
Therefore, if repainting is primarily to alter a building's primary
and accent colors, a technical factor of paint accumulation should
be taken into consideration. When paint builds up to a thickness
of approximately 1/16~ (approximately 1630 layers), one or more
extra coats of paint may be enough to trigger cracking and peeling
in limited or even widespread areas of the building's surface.
This results because excessively thick paint is less able to withstand
the shrinkage or pull of an additional coat as it dries and is
also less able to tolerate thermal stresses. Thick paint invariably
fails at the weakest point of adhesion--the oldest layers next
to the wood. Cracking and peeling follow. Therefore, if there
are no signs of paint failure, it may be somewhat risky to add
still another layer of unneeded paint simply for color's sake
(extreme changes in color may also require more than one coat
to provide proper hiding power and full color). When paint appears
to be nearing the critical thickness, a change of accent colors
(that is, just to limited portions of the trim) might be an acceptable
compromise without chancing cracking and peeling of paint on wooden
If the decision to repaint is nonetheless made, the "new"
color or colors should, at a minimum, be appropriate to the style
and setting of the building. On the other hand, where the intent
is to restore or accurately reproduce the colors originally used
or those from a significant period in the building's evolution,
they should be based on the results of a paint analysis.(5)
(5) See the Reading List for paint research and documentation
information. See also "The Secretary of the Interior's Standards
for Historic Preservation Projects with Guidelines for Applying
the Standards" for recommended approaches on paints and finishes
within various types of project work treatments.